This disclosure relates to weatherable thermoplastic compositions, and in particular to weatherable thermoplastic polymer compositions comprising polyaryl ester blends, methods of manufacture, and uses thereof.
Thermoplastic polymers of various compositions, such as polyesters and polyester-polycarbonate copolymers, are useful in the manufacture of articles and components for a wide range of applications including as automotive parts and electronic appliances. Because of their broad use, it is often necessary for various reasons, including aesthetic and functional reasons, to provide articles and components according to targeted color specifications, which is often accomplished by incorporating dyes or pigments into the polymer melt. It can also be important that the color of the thermoplastic composition is stable after exposure to various conditions such as heat exposure, light exposure (including ultraviolet (UV) light exposure), etc. Many polymers, including the above-described polyesters and polyester-polycarbonate copolymers, have been found to be subject to yellowing after light exposure, which can adversely impact the color stability performance of a thermoplastic composition. This yellowing phenomenon, sometimes referred to as photoyellowing, can be addressed by inclusion of various additives such as UV absorbers (UVA's), stabilizers including hindered amine light stabilizers (HALS), and dyes and pigments (e.g., for color compensation or light filtration), and combinations thereof.
Polyaryl esters, as used herein, include polyesters derived from aromatic diacids (i.e., polyarylates) and from aromatic diols. Polyaryl esters are known to be susceptible to photoyellowing that has been difficult to address with known techniques and materials, especially for some colors and some shades of some colors. Accordingly, there remains a need in the art for new solutions to color stability of polyaryl esters across a variety of targeted color specifications.